Complete sheet as described and bring to next lesson. NB Keep it at 1 side of A4
Hazards associated with Volcanoes
Name of Hazard
Defintion of Hazard
Source of Defintion
Student
1
Volcanic Earthquakes
Earthquakes produced by stress changes in solid rock due to the injection or withdrawal of magma are called volcano-tectonic earthquakes (Chouet, 1993). These earthquakes can cause land to subside and can produce large ground cracks. These earthquakes can occur as rock is moving to fill in spaces where magma is no longer present. Volcano-tectonic earthquakes don't indicate that the volcano will be erupting but can occur at anytime.
A lateral eruption, also called a flank eruption or lateral blast when explosive, is a volcanic eruption that takes place on the flanks of a volcano instead of at the summit. Lateral eruptions are typical at rift zones where a volcano is breaking apart. Since it is easier for molten rock to flow laterally out the sides of weak flanks, the flank gives way before magma is pushed up through a conduit that feeds magma to the summit.
A jökulhlaup (or glacier burst) is a glacial outburst flood. Which can be triggered by geothermal heating and occasionally by a volcanic subglacial eruption.
A debris avalanche is formed when an unstable slope collapses and debris is transported away from the slope. There are two general types of debris avalanches: those that are "cold" and those that are "hot". A cold debris avalanche usually results from a slope becoming unstable whereas a hot debris avalanche is the result of volcanic activity such as volcanic earthquakes or the injection of magma which causes slope instability.
A lahar is a mudflow composed of pyroclastic debris, which flows down from a volcano and typically occurs along a river valley. Lahars have approximately the same density as concrete so can carve their way through practically anything and cause massive damage.
A Tsunami is caused by anything that rapidly displaces a large volume of water. Typically, tsunamis are caused by underwater earthquakes, but landslides, volcanic eruptions, calving icebergs, and (very rarely) meteorite impacts can also generate tsunamis. These types of events can cause large disturbances in the surface of the ocean, and when gravity pulls the water back down, the tsunami is born.
Carbon dioxide (chemical formula CO2) is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state, as a trace gas at a concentration of 0.039% by volume.
Volcanoes release more than 130 million tonnes of CO2 into the atmosphere every year. This colorless, odorless gas usually does not pose a direct hazard to life because it typically becomes diluted to low concentrations very quickly whether it is released continuously from the ground or during episodic eruptions. But in certain circumstances, CO2 may become concentrated at levels lethal to people and animals. Carbon dioxide gas is heavier than air and the gas can flow into in low-lying areas; breathing air with more than 30% CO2 can quickly induce unconsciousness and cause death. In volcanic or other areas where CO2 emissions occur, it is important to avoid small depressions and low areas that might be CO2 traps.
The effects of SO2 on people and the environment vary widely depending on (1) the amount of gas a volcano emits into the atmosphere; (2) whether the gas is injected into the troposphere or stratosphere; and (3) the regional or global wind and weather pattern that disperses the gas. Sulfur dioxide (SO2) is a colorless gas with a pungent odor that irritates skin and the tissues and mucous membranes of the eyes, nose, and throat. Sulfur dioxide chiefly affects upper respiratory tract and bronchi. The sulfate aerosols also accelerate chemical reactions that, together with the increased stratospheric chlorine levels from human-made chlorofluorocarbon (CFC) pollution, destroyed ozone and led to some of the lowest ozone levels ever observed in the atmosphere as well as acting as a precursor to acid rain.
Hydrogen fluoride (HF) is a pale yellow gas that attaches to fine ash particles, coats grass, and pollutes streams and lakes. Exposure to this powerful caustic irritant can cause conjunctivitis, skin irritation, bone degeneration and mottling of teeth. Excess fluorine results in a significant cause of death and injury in livestock during ash eruptions. Even in areas that receive just a millimeter of ash, poisoning can occur. It also promotes acid rain effects downwind of volcanoes.
Chlorine gas is emitted from volcanoes in the form of hydrochloric acid (HCl). Exposure to the gas irritates mucous membranes of the eyes and respiratory tract and may be fatal if inhaled. It is also extremely corrosive, skin contact with vapour or liquid can cause serious burns. It also causes acid rain downwind from volcanoes because HCl is extremely soluble.
Hydrogen sulfide (H2S) is an extremely hazardous, toxic compound. It is a colourless, flammable gas that can be identified in relatively low concentrations, by a characteristic rotten egg odor. The gas occurs naturally in coal pits, sulfur springs, gas wells, and as a product of decaying sulfur-containing organic matter, particularly under low oxygen conditions. It is therefore commonly encountered in places such as sewers, sewage treatment plants, manure stockpiles, mines, hot springs, and the holds of fishing ships. Industrial sources of hydrogen sulfide include petroleum and natural gas extraction and refining, pulp and paper manufacturing, rayon textile production, leather tanning, chemical manufacturing and waste disposal. At certain concentrations it can cause paralysis of the nerves in the nose meaning that you may not be able to detect it through the sense of smell.
Lava flows are streams of molten rock that pour or ooze from an erupting vent of a volcano. Lava is erupted during either nonexplosive volcanic activity or explosive lava fountains. Lava flows destroy everything in their path, but most move slowly enough that people can move out of the way. The speed at which lava moves across the ground depends on its viscosity, steepness of the ground over which it travels and the rate of lava production at the vent.
Volcanic bombs are fragments of lava more than 64mm in diameter which have been ejected from the vent of a volcano while in a partially molten state. They solidify and tend to acquire aerodynamic shapes as they travel through the air.
Lapilli are pyroclastic particles of between 2- 64mm in size. They are small enough to be carried up by the heat of an eruption fall out of the air upto 30min later at distances of upto 100km.
Volcanic ash consists of small bits of pulverized rock and glass created by volcanic eruptions less than 2 millimetres in diameter.
HAZARD: Inhaling volcanic ash may cause problems for people whose respiratory system is already compromised by disorders such as asthma or emphysema.
General term referring to the qualitative or quantitative aspects of movement of the Earth's surface from a sudden release of energy in the form of seismic waves from earthquakes. Ground motion is produced by waves that are generated by sudden slip on a fault or sudden pressure at the explosive source and travel through the Earth and along its surface. Ground shaking can cause buildings to collapse due to liquefaction, signs to fall off walls, windows to shatter, roads to crack and bridges to collapse.
Ground rupture is a visible breaking and displacement of the Earth's surface along the trace of the fault, which may be of the order of several metres in the case of major earthquakes. Ground rupture is a major risk for large engineering structures such as dams, bridges and nuclear power stations and requires careful mapping of existing faults to identify any likely to break the ground surface within the life of the structure
When a saturated soil substantially loses strength and stiffness in response to an applied stress, usually earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid.
Liquefaction occurs in saturated soils, that is, soils in which the space between individual particles is completely filled with water. This water exerts a pressure on the soil particles that influences how tightly the particles themselves are pressed together.
The difference between a tectonic event, hazard and disaster & why some tectonic activity is more hazardous than others.
Lesson Work
See powerpoint here!Self Study Work
For your allocated hazard number (e.g. Mr Burn was no 15.)Hazards associated with Volcanoes
Volcanoes release more than 130 million tonnes of CO2 into the atmosphere every year. This colorless, odorless gas usually does not pose a direct hazard to life because it typically becomes diluted to low concentrations very quickly whether it is released continuously from the ground or during episodic eruptions. But in certain circumstances, CO2 may become concentrated at levels lethal to people and animals. Carbon dioxide gas is heavier than air and the gas can flow into in low-lying areas; breathing air with more than 30% CO2 can quickly induce unconsciousness and cause death. In volcanic or other areas where CO2 emissions occur, it is important to avoid small depressions and low areas that might be CO2 traps.
http://volcanoes.usgs.gov/hazards/gas/climate.php
http://www.hpa.org.uk/Topics/ChemicalsAndPoisons/CompendiumOfChemicalHazards/SulphurDioxide/
Hydrogen fluoride (HF) is a pale yellow gas that attaches to fine ash particles, coats grass, and pollutes streams and lakes. Exposure to this powerful caustic irritant can cause conjunctivitis, skin irritation, bone degeneration and mottling of teeth. Excess fluorine results in a significant cause of death and injury in livestock during ash eruptions. Even in areas that receive just a millimeter of ash, poisoning can occur. It also promotes acid rain effects downwind of volcanoes.
http://msds.chem.ox.ac.uk/HY/hydrogen_chloride.html
http://en.wikipedia.org/wiki/Lapilli
HAZARD: Inhaling volcanic ash may cause problems for people whose respiratory system is already compromised by disorders such as asthma or emphysema.
Mackay
Hazards associated with Earthquakes
http://worldlywise.pbworks.com/w/page/26834992/The-causes-and-effects-of-earthquakes-and-how-people-respond-to-them
Liquefaction occurs in saturated soils, that is, soils in which the space between individual particles is completely filled with water. This water exerts a pressure on the soil particles that influences how tightly the particles themselves are pressed together.
http://www.ce.washington.edu/~liquefaction/html/what/what1.html